An Ultra‑Durable Windmill‑Like Hybrid Nanogenerator for Steady and Efficient Harvesting of Low‑Speed Wind Energy

Wind energy is one of the most promising and renewable energy sources;however,owing to the limitations of device structures,collecting low-speed wind energy by triboelectric nanogenerators(TENGs)is still a huge challenge.To solve this problem,an ultra-durable and highly efficient windmill-like hybrid nanogenerator(W-HNG)is developed.Herein,the W-HNG composes coupled TENG and electromagnetic generator(EMG)and adopts a rotational contact-separation mode.This unique design efficiently avoids the wear of friction materials and ensures a prolonged service life.Moreover,the generator group is separated from the wind-driven part,which successfully prevents rotation resistance induced by the friction between rotor and stator in the conventional structures,and realizes low-speed wind energy harvesting.Additionally,the output characteristics of TENG can be complementary to the different performance advantages of EMG to achieve a satisfactory power production.The device is successfully driven when the wind speed is 1.8 m s−1,and the output power of TENG and EMG can achieve 0.95 and 3.7 mW,respectively.After power management,the W-HNG has been successfully applied as a power source for electronic devices.This work provides a simple,reliable,and durable device for improved performance toward large-scale low-speed breeze energy harvesting.

Round-trip oscillation triboelectric nanogenerator with high output response and low wear to harvest random wind energy

Triboelectric nanogenerator(TENG)has made significant progress in wind energy harvesting.As the most advantageous rotary TENG among wind energy harvesters,the severe material wear and the output that fluctuates with wind speed seriously hinder the application of TENG wind energy harvesters.In this study,we propose a round-trip oscillation triboelectric nanogenerator(RTO-TENG)consisting of a crank transmission mechanism and a power generation unit.The RTO-TENG utilizes a simple crank transmission mechanism combined with a zigzag-laminated triboelectric nanogenerator(Z-TENG)to achieve high-performance constant output and low material wear.The crank transmission mechanism can realize the transformation from circular motion to arc reciprocating motion,converting the random wind energy into bi-directional kinetic energy,driving the vertical contact and separation of the Z-TENG.Due to the low transmission ratio(1:1)of the crank transmission mechanism and the consistent frequency of the Z-TENG contact–separation with that of the pendulum,the RTO-TENG’s power generation unit(10 Z-TENGs)is insensitive to changes in wind speed,resulting in a constant and stable output response at various speeds.After 480,000 cycles,the output of RTO-TENG decreased by only 0.9%compared to the initial value of 6μC,and the scanning electron microscopy(SEM)images of the polytetrafluoroethylene(PTFE)film showed no significant wear on the surface of the friction layer,demonstrating excellent output stability and abrasion resistance of the RTO-TENG wind energy collector’s material.The equipped energy management module,based on a gas discharge tube switch,can further enhance the output performance of the RTO-TENG.After optimizing its inductor parameter L to match the load capacitor,it can charge a 220μF load capacitor to 13.4 V in 40 s,resulting in a 298%improvement in charging speed compared to the voltage of 4.48 V without the management module.Therefore,the RTO-TENG can efficiently provide power to low-power small electronic devices for Internet of Things(IoTs),such as road traffic warning signs and thermo-hygrometers.

Recent progress on flutter‐based wind energy harvesting

Wind energy harvesting technology can convert wind energy into electric energy to supply power for microelectronic devices.It has great potential in many specific applications and environments,such as remote areas,sea surfaces,mountains,and so on.Over the past few years,flutter‐based wind energy harvesting,which generates electric energy based on the limit cycle oscillation created by structural aeroelastic instability,has received increasing attention,and as a consequence,different energy harvesting structures,theories,and methods have been proposed.In this paper,three types of flutter‐based energy harvesters(FEHs)including airfoil‐based,flat plate‐based,and flexible body‐based FEHs are reviewed,and related concepts and theoretical models are introduced.The recent progress in FEH performance enhancement methods is classified into structural improvement and optimization,the introduction of nonlinearity,and hybrid structures and mechanisms.Finally,the main FEH challenges are summarized,and future research directions are discussed.

Self-powered Internet of Things sensing node based on triboelectric nanogenerator for sustainable environmental monitoring

The myriad sensing nodes in the Internet of Things(IoT)are mainly powered by battery,which has limited the lifespan and increased the maintenance costs.Herein,a self-powered IoT sensing node based on triboelectric nanogenerator(TENG)is proposed for the sustainable environmental monitoring.The wind powered TENG(W-TENG)is adopted in freestanding mode with the rabbit hair and six pairs of finger electrodes.With the energy management module,the weak electrical energy from WTENG can be converted into a stable direct current(DC)2.5 V voltage for the operation of the IoT sensing node.When the storage energy exceeds 4.4 V,the node can be activated,then the microprogrammed control unit(MCU)transmits the monitoring data.Thereafter,the monitoring data will be identified and relayed to the IoT cloud platform by narrowband IoT(NBIoT)module.At a wind speed of 8.4 m/s,the node can realize the wireless monitoring and data transmission for temperature and atmosphere pressure every 30 s.This work has provided a universal strategy for sustainable IoT sensing nodes powered by environmental micro-nano mechanical energy and exhibited potential applications in IoT,big data,and environmental monitoring.

Single-material-substrated triboelectric–electromagnetic hybrid generator for self-powered multifunctional sensing in intelligent greenhouse

The environmental micro-energy harvested by the triboelectric–electromagnetic hybrid generator(TEHG)can power sensors and Internet of Things(IoT)nodes in smart agriculture.However,the separation structure of traditional TEHG raises the complexity of form and material,which is harmful to the miniaturization of the device.Herein,a single-material-substrated triboelectric–electromagnetic hybrid generator(SMS-TEHG)based on the flexible magnets is designed to achieve the structural integration of triboelectric nanogenerator(TENG)and electromagnetic generator(EMG).The flexible magnets serve as the electropositive triboelectric materials for TENG and the magnetic materials for EMG,simplifying the structural complexity of TEHG.The open-circuit voltage(VOC)of the TENG and EMG are 187.2 and 9.0 V at 300 rpm,respectively.After 30,000 cycles of stability testing,the VOC of the TENG and EMG retain about 95.6%and 99.3%,respectively.Additionally,the self-powered applications driven by SMS-TEHG in intelligent greenhouse have been successfully demonstrated,such as crop light supplementation,rain monitoring,and wireless temperature and humidity sensing.This work provides a new design for TEHG and possibilities for applying TEHG and IoT in smart agriculture.

High-voltage output triboelectric nanogenerator with DC/AC optimal combination method

The high-voltage power source is one of the important research directions of triboelectric nanogenerator(TENG).In this paper,a high-voltage output TENG(HVO-TENG)is proposed with direct current/alternating current(DC/AC)optimal combination method for wind energy harvesting.Through the optimal design of a direct current generation unit(DCGU)and an alternating current generation unit(ACGU),the HVO-TENG can produce DC voltage of 21.5 kV and AC voltage of 200 V,simultaneously.The HVOTENG can continuously illuminate more than 6,000 light emitting diodes(LEDs),which is enough to drive more possible applications of TENG.Besides,this paper explored application experiments on HVO-TENG.Demonstrative experiments indicate that the high-voltage DC output is used for producing ozone,while the AC output can light up ultraviolet(UV)LEDs.The HVOTENG can increase the ozone concentration(C)in an airtight container to 3 parts per million(ppm)after 7 h and continuously light up UV LEDs.All these demonstrations verify that the HVO-TENG has important guiding significance for designing high performance TENG.